this is one of the most frequently asked questions about linux. I think if you dont know much about linux yet, you have to first get to know what linux is. There are so many distributions of linux out there, there will be definitely one distro which is suitable for every user. You cannot answer the question which linux is the best, because it depends on what you are going to do with it. On the other hand, everyone has another favorite distro. Fortunately, linux is able to handle nearly everything from low-cost, low-power plug computers and netbooks over desktop systems with multimedia capabilities as well as strong server applications and cluster computing. You can use linux on several platforms like arm and the common "PC" (x86 and 64-bit). The best thing about linux is that there is a strong user community and software directly from the package repository so that you can update and extend your linux system with ease.

The most important thing for someone starting with linux in my opinion is, that you must be willing to learn and take time for this adventure - you wont regret it.

If you want to know more, please answer first what you know about linux, which OS you are using right now, how experienced you are with computers and what you want to do with your linux system.

Fedora Core is a great mainstream distro. On the ARM platform however, they provide a root file system, and leave you on your own to build a kernel to hitch it up to. If you aren't already strong on Linux, don't bother. There aren't a lot of packages available for it yet either. Oh, and if you want graphics (more important to the OpenRD than SheevaPlug) then you'll have to add those packages after the fact.http://fedoraproject.org/wiki/Architectures/ARM

Ubuntu is a great distro (built on Debian) but as of version 9.4 they quit supporting the ArmV5 processor in the Kirkwood platform (Sheevaplug, GuruPlug, OpenRD). If you use Gumstix they run ArmV7 so you're still in.http://www.ubuntu.com/products/whatisubuntu/arm

Angstrom Linux is pretty slick. They have an on-line builder, so you can choose the packages you want. They have good kernel support as well. There are fewer packages than some of the other distros, but they're still good.http://www.angstrom-distribution.org/

Debian Lenny - Deiban Lenny is the longer term supported version of Debian Linux. It's solid, but Squeeze has more packages, and I've not had any problems with it crashing on me. On the OpenRD-Client (the big brother of Sheeva/Guru Plug) I run a custom kernel put together by Frans Meulenbroeks http://james.99k.org/openrd.html which includes all the drivers for video and sound on the OpenRD (it's not mainstream yet). He's done a much better job with it than I've been able to do on my own, and I've had really good luck with it. At any rate, Squeeze seems as solid as Lenny to me, so I'm sticking with it.